Maximum Depth of Binary Tree

来源：Leetcode

原帖：https://oj.leetcode.com/problems/maximum-depth-of-binary-tree/

题目：
Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

代码：

 /**  
  * Definition for binary tree  
  * struct TreeNode {  
  *   int val;  
  *   TreeNode *left;  
  *   TreeNode *right;  
  *   TreeNode(int x) : val(x), left(NULL), right(NULL) {}  
  * };  
  */  
 class Solution {  
 public:  
   int maxDepth(TreeNode *root) {  
     if (!root) return 0;  
     return 1 + max(maxDepth(root->left), maxDepth(root->right));  
   }  
 };